/***
	快速排序不稳定
***/
Array.prototype.quickSort = function(){
	if(this.length < 2){
		 return this ;	
	} 
	var
	less = [],greater = [],
	poivtIndex = Math.ceil(this.length/2),
	poivt = this.splice(poivtIndex,1)[0];
	
	for( var index = 0 ; index < this.length ; index++){
		if(this[index] < poivt){
			less.push(this[index]);
		}else{
			greater.push(this[index]);
		}
	}

	return less.quickSort().concat(poivt,greater.quickSort());
}